1. Field of the Invention
The present invention relates generally to network data transmission and, more particularly, to data transmission through cable modem systems.
2. Description of Related Art
In cable modem systems, a cable modem termination system (CMTS) at one end of a cable network typically services multiple cable modems (CMs) connected to the cable network. CMs are generally installed locally at the end-user's location, and communicate with the CMTS, which may be installed at a cable company's facility. The CMTS transmits data and messages to the CMs in a “downstream” direction and receives data bursts from the CMs in an “upstream” direction.
Data over Cable Service Interface Specification (DOCSIS) is a commonly used CM protocol that defines interface requirements for CMs. DOCSIS 2.0, for example, builds upon the capabilities of DOCSIS 1.0 and DOCSIS 1.1 and adds throughput in the upstream portion of the cable system. This increased upstream data capacity enables symmetrical and time-critical services such as videoconferencing and peer-to-peer applications. When sharing a communication channel with a CMTS, the CMs may use modulation schemes in which the modems transmit data bursts to the CMTS during designated time intervals. DOCSIS 2.0, for example, includes two modulation techniques: S-CDMA (synchronous code division multiple access) and A-TDMA (advanced frequency agile time division multiple access).
CMTSs typically receive data though a number of physical ports and further distinguish between different frequencies or “channels” of data using a number of internal receivers. Current CMTSs typically have a fixed relationship between their internal receiver(s) and the physical port(s). Such a static relationship between receivers and physical ports in a CMTS may cause data congestion or CM configuration restraints when, for example, the load on the ports changes dynamically, or when multiple modulation techniques (e.g., S-CDMA and A-TDMA) are used.
Therefore, there exists a need to more efficiently utilize CMTS capacity in cable modem systems.